So - what's the difference?

  There is a commercial on television that shows a woman looking at a distant light that gets smaller and smaller.  She appears happy to be able to see the "candle".  The ad is for Centrum Silver and it claims, rightly, that is contains Lutein.
  Lutein is used to slow the progress of Macular Degeneration, at least that's why I use it as advised by my Optometrist.  It is available over the counter in 6mg or 20mg capsules, or sometimes 10mg cap.
  Here's my beef, Centrum Silver for Men contains 300mcg, that's mcg.  Mcg stands for microgram.  One mcg is equal to .001 mg.  So Centrum Silver contains .3mg or 3/10 mg, or 3 tenths of 1 milligram - or practically just enough to be able to advertise that it's in the pill.   It's not enough to make much of a difference.
  Oh, by the way; the woman has blue eyes.

Photo: www.welldynehealth.com, it shows the label from Centrum Silver